Helix panics on goto_window_center when lines fill less than half the screen

[iobtl]

Summary

Helix panics when trying to go to center of window (when less than half the screen populated)

helixcrash3.mov

Reproduction Steps

I tried this:

1. RUST_BACKTRACE=1 hx
2. Navigate to some file (https://github.com/helix-editor/helix/blob/master/helix-term/src/ui/picker.rs in this example)
3. ge
4. zt
5. gc

I expected this to happen:

Probably something similar to align_view_center

Instead, this happened:

hx panics and crashes.

Helix log

~/.cache/helix/helix.log

helix.log only has a bunch of LSP messages, but here is the backtrace, which seems to be clear enough where the problem is:

thread 'main' panicked at 'assertion failed: min <= max', /rustc/4b91a6ea7258a947e59c6522cd5898e7c0a6a88f/library/core/src/cmp.rs:846:9
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: helix_term::commands::goto_window
   4: helix_term::ui::editor::EditorView::handle_keymap_event::{{closure}}
   5: helix_term::ui::editor::EditorView::handle_keymap_event
   6: <helix_term::ui::editor::EditorView as helix_term::compositor::Component>::handle_event
   7: helix_term::compositor::Compositor::handle_event
   8: helix_term::application::Application::event_loop_until_idle::{{closure}}
   9: helix_term::application::Application::run::{{closure}}
  10: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
  11: hx::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Platform

macOS

Terminal Emulator

alacritty 0.10.1 (2844606)

Helix Version

22.12-262-g2bebc504

[iobtl]

I encountered this bug when remapping C-d = ["half_page_down", "goto_window_center"] and doing ge, C-d, C-d, which crashes the program (with an identical error message as the one in the video).

(Will be happy to take on this bug if it's deemed to be of significant concern, unless the fix is trivially obvious to one of the maintainers)

[pascalkuthe]

can reproduce, I will look into this since I work on this code last, thanks for reporting 👍

[iobtl]

Sounds good!